Lsof (LiSt Open Files) lists information about files that are open by the
running processes.  An open file may be a regular file, a directory, a block
special file, a character special file, an executing text reference, a
library, a stream or a network file (Internet socket, NFS file or Unix domain
socket).

Main use of lsof  will be for writing cross-platforms scripts.
OpenBSD includes fstat(1), which serves the same basic purpose.
